Wireless Motion Detector Transmitter
                                                 that passes infrared in the 5 to 14µm range
                                                 which is most sensitive to human body
Introduction______________                       radiation. As an object that emits infrared
                                                 passes in front of the PIR, its output goes
                                                 either more positive or more negative.
Motion detectors are used mostly to turn         Since the output signal is very small, it
lights on when they sense movement of            passes through two stages of amplification
people or vehicles. The detector device is       having a total maximum gain of about
often built into an outdoor flood or porch       10,000.     Range      is    controlled  by
light to illuminate a driveway or porch at       potentiometer R5 which adjusts the gain
night making it easier to enter your house       from 1000 to 10,000.
without having to leave the light on while
                                                  R1 and C1 filter any noise from the power
you are away. They also add security by
                                                 that feeds the PIR and R2 is a load for the
turning the outside light on at night when
                                                 FET within the PIR. IC1 is either a Maxim
motion is detected even while you are at
                                                 MAX407 or Linear Technologies LT1495
                                                 dual micropower operational amplifier. R3,
Detectors are available that are intended for    R4 and C2 set the IC1A amplifier gain and
use with security systems to sound an alarm      reference voltage and C3 limits its
or summon police when motion is detected         bandwidth to about 10Hz. C4 couples the
even during daytime but these are usually        output of IC1A into IC1B. R5, R6, R7 and
expensive and must be wired to the alarm         R10 set the gain of IC1B and C5 limits its
control box. If security is your main concern,   bandwidth to about 10Hz. R7 and R9 set its
this may be a good choice.                       bias to 2.5 volts.
However, it is often convenient just to know     IC2 is either a Maxim MAX922 or a Linear
when a person is approaching your front or       Technologies LTC1440 dual micropower
back door or when a vehicle enters your          comparator. IC2A functions as a window
driveway even in daytime.         If several     comparator and also functions together with
detectors are used, you can also identify        IC2B as a single shot. When no motion
where the motion is taking place.                occurs and there is no output from the PIR,
                                                 the output of IC1B at pin 7 rests at 2.5 volts.
The Wireless Motion Detector system
                                                 Resistive divider R11, R12 and R13 apply a
described here is designed to detect motion
                                                 bias input through R14 and R15 to pin 5 and
over a narrow field of less than ten degrees
                                                 pin 6 of IC2A. The level at pin 5 is 250MV
so that the area is easily identified. The
                                                 more positive than at pin 6, forcing output
motion transmitter includes a motion
                                                 pin 8 to a down level.
detector, amplifier, encoder, transmitter and
a battery operated power supply. It can be       When motion is detected that produces a
located indoors or outdoors. When outdoors,      positive transition at IC1B pin 1, then pin 6
it can be attached to the wall of a house, to    of IC2A is forced up through D2 and
a tree or to a post using a Velcro fastener      becomes more positive than pin 5. This
but should be protected from the weather         causes output pin 8 to go up. If the motion
with some type of housing such as by             produces a negative transition at IC1B pin 1
placing it in an unoccupied birdhouse.           then IC2A pin 5 is forced down through D1
                                                 which also causes IC2A output pin 8 to go
How it works______________
                                                 The positive transition at IC2A pin 8 couples
                                                 through C6 into IC2B, turning it on and
Transmitter                                      causing its output pin 1 to go down. This
Figure 1 is a schematic of the transmitter.      down level pulls IC2A pin 5 down through
PIR is a NiCERA RE200B dual element              D3 and latches it down until C6 discharges
pyroelectric infrared sensor with a built-in     through R17 and, or R18. Program jumper
FET amplifier. It also has an optical filter     PJ places a lower value R17 in parallel with
                                                 R18 to reduce the time constant during
ktpir.doc                                                                                     1
Wireless Motion Detector Transmitter
testing, When C6 discharges below the             are mounted feed the leads from a 9 volt
reference voltage at pin 3, IC2B turns off        battery connector through a hole in the
and pin 1 goes up again. The C6, R15, R18         battery compartment of the enclosure and
time constant is about 90 seconds without         solder them to the transmitter board holes
PJ and 1 second with PJ. R19, R20 and             marked plus V and minus V.
R21 produce hysteresis to avoid jitter in the
                                                  The antenna can be a stiff piece of wire 6.7
IC2B output during the slow discharge of C6
                                                  inches long. Feed it through a hole in the
and they also set its reference. C7 R16 and
                                                  enclosure and attach it to the terminal block.
D4 couple a narrow negative pulse into
Holtek HT680 encoder IC3 to initiate a
transmit sequence.                                Testing
Upon being triggered by IC2B, the encoder         Connect a 9 volt battery to the transmitter.
generates three groups of bits containing         Set transmitter switch SA positions 1, 2, 3
data and address information and serially         and 4 OFF and position 5 on to identify it as
sends them to transmit module TM1V. The           detector 1. You are now ready to detect
encoder can be programmed by 4 position           motion and transmit data to a receiver.
DIP switch SA positions 1, 2 ,3 and 4 for 16      Repeat the above for any additional
different addresses so that more than one         detectors, using SA positions 6, 7 or 8 to
set of transmitters and receivers can be          identify each transmitter.
used in close proximity without interference.
Its data inputs can also be programmed by
positions 5, 6, 7 and 8 to identify the
transmitter as number 1, 2, 3 or 4. Only one
of these switches should be ON.
The circuits are powered with 5 volts
through reverse polarity protection diode D5
and Telcom TC55RP5002EZB low dropout
micropower regulator IC4 by a          9 volt
battery. Because of the micropower circuits
used in this transmitter, standby current is
only 20 microamperes which is about 100
times less than that of other motion


PC Board
The PC board is designed to fit in a Serpac
model 211 enclosure available from Digi-
Key and Allied. Cut a 1.2 inch round hole in
the enclosure cover and attach a Fresnel
lens inside with its grooves facing in. Hold it
in place with pieces of scotch tape along the
edges. Place an O ring under the PIR to
space it off the board and solder it in place.
This spacing ensures proper focal distance
between the Fresnel lens in the enclosure
cover and the PIR. Sockets are used for all
of the DIP ICs. To assemble the board
mount all of the small components first,
then add the sockets. After all components
ktpir.doc                                                                                     2
      Wireless Motion Detector Transmitter

                         R1 10K

               +    C1
                    10                                                                                                 R11                                      R19
                                C3        .01                                      C5           .01
                                                            R8                                                         2M                                      10M
                                                                                                              D1                         D3
      1                          R4 10M                                            R10 10M
          2                      5                                             2        _                                        5 _                                  4    _
PIR                                +
                                                          C4 1                                                         R14 10M                     C6 10
      3            R2                                                                                          R12                                  +
                                      IC1A                                              IC1B                                         IC2A                                  IC2B
                   100K                          7               +                                    1       200K                            8                                   1
                                      _                                                                                R15 10M                     C7
                                                                                        +                                            +                                     +
                                 6                                              3                                                6                .01                 3
                    R3                                    R7           R9
                   100K                                   100K        10M                                                                                R17
                                                                                                              D2                                        100K              R21 10M
                                     R5                                                                                R13 R16
                    C2     +         1M                                                                                2M 10M                           R18           R20
                     1                      R6 100K                                                                                                     10M
                                                                                                                                            D4    PJ                  3M

              IC1 = LT1495
              PIN 1 = +5
              PIN 4 = GND                                            R22
              IC1 = LTC1441                                          390K
              PIN 7 = +5                                                                                                                                                  ANTENNA
              PIN 2 = GND                                             9     8       7       6         5   4   3    2   1

                                                                                             IC3                                              TM1V
                                                                                            HT-680                                          TRANSMIT
                    IC4                              +5               10 11 12 13 14 15                       16 17 18
                                                                                                                                          1 2 3 4 5 6
  +                            C8 +         C9

                               100          .1

                                                                     1     2        3       4     5       6   7    8
  6 - 9 VOLTS                                                SA                                                                                    +5


          WIRELESS MOTION DETECTOR TRANSMITTER                                                                                                    FIGURE 2

                   c 1998, 1999
                   Glolab Corporation                                                                            
                   134 Van Voorhis                                                                                         email
                   Wappingers Falls, NY 12590                                                                              fax (914) 297-9772
Wireless Motion Detector Transmitter

Parts List
                        Wireless Motion Detector Transmitter parts

                        R1 - 10K 1/8 watt 5%
                        R2, R3, R6, R7, R17 - 100K 1/8 watt 5%
                        R4, R8, R9, R10, R14 R15 - 10 MEG 1/8 watt 5%
                        R16, R18, R19, R21 - 10 MEG 1/8 watt 5%
                        R20 - 3 MEG 1/8 watt 5%
                        R5 - 1 MEG potentiometer
                        R11, R13 - 2 MEG 1/8 watt 5%
                        R12 - 200K 1/8 watt 5%
                        R22 - 390K 1/8 watt 5%
                        C1 - 10 MFD 16 volt low leakage electrolytic
                        C2, C4 - 1 MFD 16 volt tantalum
                        C3, C5, C7 - .01 MFD 50 metalized film
                        C6 - 10 MFD 6.3 volt tantalum
                        C8 -100 MFD 10 low leakage electrolytic
                        C9 - .1 MFD 50 volt metalized film
                        D1, D2, D3, D4, D5 - 1N914B diode
                        SA - 8 position DIP switch
                        IC sockets - two 8 pin
                        IC socket 18 pin
                        O-ring spacer
                        PIR - RE200B pyroelectric infrared sensor
                        IC1 - Linear LT1495 micropower op amp
                        IC2 - Linear LTC1441 micropower comparator
                        IC3 - Holtek HT680 encoder
                        IC4 - Telcom TC55RP5002EZB 5 volt regulator
                        Glolab TM1V Transmit module
                        9 volt battery connector
                        1 position antenna terminal block
                        6.7 inch antenna wire
                        Transmit circuit board
                        Infrared Fresnel lens FL65 - .65” focal length
                        Enclosure - Serpac 211

© 1998
Glolab Inc.                            
134 Van Voorhis                                  email
Wappingers Falls, NY 12590                       fax (914) 297-9772

Ktpir parts

To top